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In the generalized quasilinear approximation (GQLA) (Marston et al., Phys. Rev. Lett., vol. 116, 2016, 214501), a threshold wavenumber ($k_0$) in the direction of translational symmetry segregates the total into large- ($l$) and small-scale ($h$) fields. While the governing equation for the large-scale field is fully nonlinear, that for the small scales is linearized with respect to the large-scale field. In addition, some nonlinear triad interactions are omitted in the GQLA. Herein, the GQLA is applied to two-dimensional planar Rayleigh–Bénard convection (RBC). A scale separation between the large-scale convection rolls and small-scale turbulent fluctuations is typical in RBC. The present work explores the efficacy of GQLA in capturing the scale-by-scale energy transfer processes in RBC. The initial condition for the GQLA simulations was either the statistically stationary state obtained in direct numerical simulation (DNS) or random fluctuations superimposed on the linear conductive temperature profile and $\boldsymbol {u}=0$. The GQLA simulations can capture the convection rolls for $k_0$ larger than or equal to the dominant wavenumber for thermal driving of the flow ($k_0 \ge k_{\hat {Q}}$). Additionally, the GQLA emulates the fully nonlinear dynamics for $k_0$ larger than or equal to the first harmonic of the convection-roll wavenumber ($k_0 \ge 2k_{roll}$). In the intermediate regime with $2k_{roll} > k_0 \ge k_{\hat {Q}}$, the dynamics captured in GQLA simulations is different from the DNS. In DNS, two primary energy transfer processes dominate: (i) the energy transfer to/from the convection rolls and (ii) the scale-by-scale inverse kinetic energy and forward thermal energy cascades mediated by the convection rolls. The fully nonlinear dynamics is emulated by GQLA when these energy transfer processes are faithfully reproduced. Utilizing the framework of altering the triad interactions in GQLA, an additional intrusive calculation, including target triad interactions, is performed here to study their influence. This intrusive calculation shows that the convection rolls are not captured in GQLA for $k_0 < k_{\hat {Q}}$ because of the exclusion of the $h \to l \to l$ and $l \to h \to h$ triad interactions in GQLA. The inclusion of these triad interactions in the intrusive calculation yields the convection rolls, and the reproduced dynamics is similar to that of the intermediate GQLA regime with $2k_{roll} > k_0 \ge k_{\hat {Q}}$.
We all consume the humanities through our engagement with the cultural, creative, and historical materials that influence our views on ourselves, others, and the world around us. However, can consumers also be considered humanists? We argue the answer is yes when consumption choices become symbols and expressions of one’s authentic self and meaningful connective points to others. Using hard-core surfing enthusiasts and thrifters as examples, we introduce the notion of fringe consumption as a form of cultural entrepreneurship and public expression of the humanities that centers individuality, authenticity, and otherness in an otherwise dominant mainstream environment that pushes people to always want more of the same.
The COVID-19 pandemic negatively affected students’ mental health, increasing pre-existing psychosocial vulnerabilities. University students worldwide have presented differences in their mental health status; however, cross-country studies comparing students’ mental health during the pandemic are lacking.
Aims
To investigate potential differences between university students from Brazil and those from Germany with respect to (a) depressive symptoms and alcohol and drug consumption, (b) social and emotional aspects (loneliness, self-efficacy, perceived stress, social support and resilience) and (c) attitudes towards vaccination.
Method
Two online cross-sectional studies were conducted with university students during the COVID-19 pandemic in Brazil (November 2021 to March 2022) and in Germany (April to May 2022). Depressive symptoms, alcohol consumption, loneliness, self-efficacy, perceived stress, social support, resilience, sociodemographic information and attitudes towards vaccination were assessed. Data were analysed using univariate and bivariate models.
Results
The total sample comprised N = 7911 university students, with n = 2437 from Brazil and n = 5474 from Germany. Brazilian students presented significantly more depressive symptoms and suicidal thoughts, higher levels of perceived stress, higher frequency of drug or substance consumption, and lower levels of perceived social support and resilience than German students, whereas German students presented higher levels of loneliness than Brazilian students. A more favourable opinion towards vaccinations in general was found among Brazilian students compared with German students.
Conclusions
In both countries, low-threshold (online) counselling targeting university students is needed. The differences between the samples could indicate country and/or cultural differences which justify further research in this area.
Health care and health security are the fundamental pillars of disaster preparedness and crisis management. An established routine health care is necessary for any society, enabling full access to care and fulfilling the rights of every individual. Health security, on the other hand, is what a society needs to be flexible in managing an unexpected situation. To overcome a disaster with minimal damage or to avert such a critical situation, health care and health security should exist simultaneously. Thus, resilience in disaster preparedness and crisis management requires investment in both health care and health security. This ensures local public health services and infrastructure, local ambulances, both acute and chronic care referral systems, prompt vaccinations, and prevention of communicable diseases to name but a few. These measures which have proven to be the most sensitive evaluation of fair governance are critically absent in several nations, particularly in areas with long-standing conflicts. Strengthening health care and health security measures are paramount to the maintenance of the health system in peace and recovery of health delivery post-conflict and require political and economic considerations.
The essay aims at discussing visual arts and gender issues, with specific reference to models for female empowerment by means of aesthetic paradigm shifts. These took place thanks to pioneering video artists in the 1990s and were then upheld by new millennium music pop stars in highly influential videoclips. I argue that videos by artists such as Pipilotti Rist, Cheryl Donegan, Mona Hatoum, Andrea Fraser, and Susan Hiller matter today for how they tackled gender issues by means of the moving image, especially by challenging the male gaze and creating gender specific perspectives long before women could claim a similar influence on the television business and in the movie industry. They offered ground-breaking strategies in visual representation and video narratives of considerable impact since they were later adopted in public life, particularly through female pop stars’ aesthetic transfer into music videoclips, such as with Beyoncé. In this regard, I observe how art historical references are applied in recent videoclips to challenge the male gaze, letting a threefold strategy emerge: thematic reprise, iconographic substitution, and aesthetic transposition.
This contribution highlights the importance of institutional dispute prevention not just to prevent the proliferation of formal legal disputes between states and foreign investors, but also to preserve the relationship between investors and states and enable investment retention and expansion. Drawing from empirical studies and survey findings, as well as the World Bank's country experience of working on investment policy and promotion frameworks, this contribution provides an overview of the World Bank's experience in implementing such mechanisms globally.1
To assess the health technology assessment (HTA) process in Greece from its establishment in 2018 until 2023 in terms of timeliness and productivity.
Methods
Data were collected from the HTA Committee’s database and other publicly available sources. The overall study timeframe was divided into three periods: (i) July 2018–January 2020, (ii) January 2020–July 2021, and (iii) July 2021–February 2023.
Results
During the study period, a total of 1,157 applications for medicinal products (MPs) (including 219 new active substances (NAS) and orphans) were submitted to the HTA Committee. The number of HTA recommendations increased from 60 (first period) to 641 (third period), while the backlog of MPs pending HTA and price negotiations decreased from 89 and 106 (January 2020) to 8 and 44 (February 2023), respectively. The median time intervals for all application types decreased significantly over time. In February 2023, the median time for clinical data assessment of NAS (excluding orphans) almost halved from 207 days in the first period to 114 days; median times for NAS and orphans from regulatory approval to HTA application were 420 and 457 days, and from HTA application to reimbursement 228 and 417 days, respectively.
Conclusions
The performance of the HTA process in Greece improved significantly over time, with increased MP appraisals, backlog reduction, and decreased timelines. Delays in reimbursement of NAS were mainly caused by the long gap between regulatory approval and HTA application. Overall, HTA review times in Greece are now on par with that of well-established European HTA systems.
Countries frequently use health technology assessment (HTA) to set priorities for introducing new interventions or evaluating existing interventions; however, applying the tool effectively is heavily dependent on a country’s resources and capacity. Infrastructure and data, technical expertise, broad stakeholder involvement, and financial support are required to improve HTA processes. In the Asia-Pacific, HTAsiaLink was established to facilitate this practice, but strengthening and legitimizing this organization are needed to maximize its potential to support HTA institutionalization in the region. To realize this objective, HTAsiaLink can serve as a center of excellence while providing experiential learning and sharing information. As a learning hub, HTAsiaLink can share resources—particularly data—that can contribute to joint HTAs as done in the European Union and strengthen capacity in countries needing to develop their HTA expertise.
This article studies the dynamical behaviour of classical solutions of a hyperbolic system of balance laws, derived from a chemotaxis model with logarithmic sensitivity, with time-dependent boundary conditions. It is shown that under suitable assumptions on the boundary data, solutions starting in the $H^2$-space exist globally in time and the differences between the solutions and their corresponding boundary data converge to zero as time goes to infinity. There is no smallness restriction on the magnitude of the initial perturbations. Moreover, numerical simulations show that the assumptions on the boundary data are necessary for the above-mentioned results to hold true. In addition, numerical results indicate that the solutions converge asymptotically to time-periodic states if the boundary data are time-periodic.
Like other regions of the world, academic freedom is on the decline in Africa. While there are some generic factors accounting for this phenomenon worldwide, others are fundamentally unique to the African context. These are related principally to the subject matter of coloniality of higher education on the continent. This study addresses these matters by, among others, discussing the origins of the university in pre-modern Africa and the place of academic freedom in it. This development is followed by the emergence of university education in Europe through the application of the liberal script and which contributed to the sidelining and eventual general demise of higher education institutions with their roots in pre-modern Africa. The work contends that while one may trace the origins of the university/academic freedom to Africa, academic freedom as it stands today is shaped by the liberal script with hardly any reference to the root of higher education in Africa. Therefore, the meaning, understanding and application of academic freedom do not reflect the realities of higher education in Africa. This work proposes the adoption of a relative universalist approach, as opposed to the liberal approach, which is clothed with universality, but in reality, it is a reflection of a European idea of academic freedom. This approach is considered necessary to reflect the African reality of academic freedom which will help to identify effective advocacy tools to promote and protect academic freedom in Africa and thereby make academic freedom more meaningful for application in the region.
This manifesto is a case study of a new method of configuring Humanities wisdom. Following the 2008 financial crisis, students and parents questioned the value of Humanities disciplines in relation to debt and future employment prospects. The experiment described here is an attempt at Arizona State University to reinvigorate humanistic pedagogy by means of an entirely new transdisciplinary Bachelor of Arts degree that abandons the disciplinary nomenclature that goes back to Aristotle and was instantiated, then ossified, in the twentieth-century university. The problem, it is argued, is not in the content, but in the naming: History, Literature, Philosophy, Language, and Religion. The experiment is to begin not with these discrete and seemingly moribund bodies of knowledge, but with the most pressing concerns of present and future publics. We name these, and so we name the new degree, Culture–Technology–Environment. The manifesto describes the design and content of the degree and raises the hope that curricular innovations of this kind will create Humanities-wise citizens for the future.
Shear-induced self-diffusion is a fundamental mode of transport in granular flows. Yet its critical behaviour and dependence on the particle solid fraction are still unclear. Here, we rationalize these dependencies by performing two-dimensional pressure-imposed numerical simulations of dense non-Brownian frictional suspensions. Our results, combined with existing numerical data on inertial granular flows, show that the shear-induced diffusion coefficients of both systems can be captured by a single function of the distance to jamming. They further show that the grain diffusive behaviour is underpinned by a specific random walk process, having a constant elementary step length driven at a frequency that increases with the solid fraction. The proposed scaling laws pave the way for a better understanding of mixing processes in granular media.
Flying insects exhibit remarkable capabilities in coordinating their olfactory sensory system and flapping wings during odour plume-tracking flights. While observations have indicated that their flapping wing motion can ‘sniff’ up the incoming plumes for better odour sampling range, how flapping motion impacts the odour concentration field around the antennae is unknown. Here, we reconstruct the body and wing kinematics of a forwards-flying butterfly based on high-speed images. Using an in-house computational fluid dynamics solver, we simulate the unsteady flow field and odourant transport process by solving the Navier–Stokes and odourant advection-diffusion equations. Our results show that, during flapping flight, the interaction between wing leading-edge vortices and antenna vortices strengthens the circulation of antenna vortices by over two-fold compared with cases without flapping motion, leading to a significant increase in odour intensity fluctuation along the antennae. Specifically, the interaction between the wings and antennae amplifies odour intensity fluctuations on the antennae by up to 8.4 fold. This enhancement is critical in preventing odour fatigue during odour-tracking flights. Further analysis reveals that this interaction is influenced by the inter-antennal angle. Adjusting this angle allows insects to balance between resistance to odour fatigue and the breadth of odour sampling. Narrower inter-antennal angles enhance fatigue resistance, while wider angles extend the sampling range but reduce resistance. Additionally, our findings suggest that while the flexibility of the wings and the thorax's pitching motion in butterflies do influence odour fluctuation, their impact is relatively secondary to that of the wing–antenna interaction.
This paper presents a new topology for a microwave active mixer using compact microstrip diplexer constituted from two dual-mode open loop resonators. The resonators are tuned to the radio frequency (RF) and local-oscillator (LO) frequencies, respectively, to effectively isolate the two input signals, while the diplexer output port is connected to the gate circuit of a commercial low cost GaAs pHEMT transistor. The drain circuit of the active device is connected to the load via an intermediate-frequency (IF)-modified Chebyshev low-pass filter to remove the unwanted RF and LO signals and reduce other spurious frequencies at the output of the mixer circuit. The circuit has been designed and constructed for an RF of 850 MHz, LO frequency of 1050 MHz, and an IF of 200 MHz. Experimental measurements show that the circuit provides a conversion gain of 18 dB at LO drive power of +2 dBm. It also operates satisfactorily over the RF range from 800 to 900 MHz with good image frequency rejection and stable operation.
The steady rise of international investment arbitration in recent years suggests that many states still struggle to prevent investor grievances from becoming international investment disputes and ultimately arbitration claims. The United States is not exempt from such difficulties, but it has some institutional advantages contributing to its successful approach to mitigating and managing international investment disputes. Key advantages include its practice of: (1) “internationalizing” domestic law in U.S. international investment agreements (IIAs); (2) encouraging foreign investors to pursue domestic remedies in U.S. courts; and (3) domesticating the international investment regime within the U.S. government. The U.S. experience offers some valuable lessons for the ongoing reform of the international investment regime.
Prompted by the relevant problem of temperature inversion (i.e. gradient of density anti-correlated to the gradient of temperature) in astrophysics, we introduce a novel method to model a gravitationally confined multi-component collisionless plasma in contact with a fluctuating thermal boundary. We focus on systems with anti-correlated (inverted) density and temperature profiles, with applications to solar physics. The dynamics of the plasma is analytically described via the coupling of an appropriated coarse-grained distribution function and a temporally coarse-grained Vlasov dynamics. We derive a stationary solution of the system and predict the inverted density and temperature profiles of the two species for scenarios relevant for the corona. We validate our method by comparing the analytical results with kinetic numerical simulations of the plasma dynamics in the context of the two-species Hamiltonian mean-field model. Finally, we apply our theoretical framework to the problem of the temperature inversion in the solar corona, obtaining density and temperature profiles in remarkably good agreement with the observations.
Greenberg’s Universal 42 states that all languages have pronominal categories involving at least three persons and two numbers. However, this characterization fails to capture the properties of pronouns in Japanese, which are not bundles of person, number and gender features (so-called phi-features); rather, they contain sociolinguistic information about the interlocutors. We propose that these properties are structurally determined. Following Ritter and Wiltschko, we assume that the highest layer of structure in nominals is interactional structure. As for phi-features, we adopt the standard assumption that they are represented internal to the determiner phrase (DP). We propose that the distinctive properties of Japanese pronouns follow from the hypothesis that they spell out elements of the interactional structure and not the DP. We show that the lack of phi-features in Japanese pronouns correlates with other properties of this language’s grammar. Support for this analysis comes from languages where pronouns with phi-features can optionally be used to encode formality (e.g. German and French). We propose that in these languages, formal pronouns originate within the DP but are interpreted in the interactional structure. Finally, we suggest that this analysis may extend to imposters and vocatives in that they may also be interpreted in the interactional structure.
In homotopy type theory, few constructions have proved as troublesome as the smash product. While its definition is just as direct as in classical mathematics, one quickly realises that in order to define and reason about functions over iterations of it, one has to verify an exponentially growing number of coherences. This has led to crucial results concerning smash products remaining open. One particularly important such result is the fact that the smash product forms a (1-coherent) symmetric monoidal product on the universe of pointed types. This fact was used, without a complete proof, by, for example, Brunerie ((2016) PhD thesis, Université Nice Sophia Antipolis) to construct the cup product on integral cohomology and is, more generally, a fundamental result in traditional algebraic topology. In this paper, we salvage the situation by introducing a simple informal heuristic for reasoning about functions defined over iterated smash products. We then use the heuristic to verify, for example, the hexagon and pentagon identities, thereby obtaining a proof of symmetric monoidality. We also provide a formal statement of the heuristic in terms of an induction principle concerning the construction of homotopies of functions defined over iterated smash products. The key results presented here have been formalised in the proof assistant Cubical Agda.